Sound reproducer



May 20, 1930. WOLFF 1,758,993

SOUND REPRODUCER Filed Nov. 17, 1928 lllxlllllll 2a 2,5 I Jwvvv--lllill J1/wanton IRVING. woLFF Patented May 20, 1930 ,UNITEDJ STATES' PATENT Volf-Fiel?.

IRVING WOLFF, 0F NEW YORK, N. Y., ASSIGNOR TO RADIO CORPORATION OF AMERICA,

' A CORPORATION OF DELAWARE SOUND REPOD'UCEB Application filed November 17, 19.28. SeriajlNo. 320,023.

This invention relates to an inertialess type of sound reproducers. More particularly it relates to sound reproducers in which a continuous corona discharge is provided, the .discharge being modulated by a sound modulated current such as is obtained from a radio receiver. v

It has been suggested in United States Patent No. 1,695,075, that a sound reproducer be formed by providing a continuouscorona discharge and by modulating the discharge vbyV applying a speech or sound modulated potential between the two discharge mem- GTS.

In the arrangement shown therein the source of high potential discharge energy is connected between the discharge members and the modulating potential is connected in parallel therewith. My invention relates to an improved method and construction for applying the modulating potential Vto the corona Adischarge of a sound reproducer of this type. l

vide an improved sound reproducer yof the type described in which the modulating potential is not applied between the ldischarge members. According to one form of my invention, this object is attained by applying the modulating potential between one ofthe corona discharge members and a grid-like member interposed between the two discharge members. In another form of my invention the modulating potential is applied between two grid-like membersy which are interposed between the two discharge inem` bers.

Various other methods of carrying out my invention will become apparent upon reading the following description of my invention in connection with the accompanying drawing in which y A Figure 1 illustrates an approved form of my invention: V igure 2 illustrates a modification thereof; an 4 Figure 3 -illustratesa still further modification thereof.

Referring more particularly to the draws' ing Figure 1 illustrates a modification of my invention in which members 1 and 2 are Supplied with energy from a source Shaving a suiiiciently high potential to cause a corona discharge between the members. One of the members is preferably provided with a plu- Y rality of spikes 4 anda layer of insulating material 5 through which the spikes 4 protrude. With such an arrangement the corona discharge will take place between the points of the spikes 4 and the plainl member 1.

The source 3' may be a direct` current generator, an alternating current generator, or

any other' source of either alternatin or direct current energy which has a su ciently high potential to maintain a practically continuous corona discharge between the member 1 and the spikes 4. The discharge should take place at such a high frequency as to be practically inaudible.

In this form of my invention, a grid-like member 6 is interposed between members 1 and 2. The sound modulated current for modulating the corona discharge is applied It is the object of this invention to probetween the grid-like or control member 6 and one of the corona discharge members. According to this particular modification the modulating otential is applied between the control mem er or grid 6 and the member 2 which is provided with the spikes 4. The circuit for applying the modulating potential can be traced from the grid6 through the secondary of a transformer 7, a resistance 8 and la battery 9 to the discharge member 2. The

resistance 8 and the battery 9are provided to obtain the proper grid bias for the memberp anda condenser 10 isconnected to shunt the resistance 8 and battery 94s0 as to form a path for the varying potential from transformer 7. The primary of transformer 7 may be con! given a parabolic shape and, as in Figure 1,

is interposed. between the corona discharge members. An insulating member 15 is provided for insulating the leads connected to the discharge member 12 and the control member 16. In this modification the modulating potential is applied between the plane discharge member 11 and the grid member 16. The circuit connecting these members includes the elements 17, 18, 19 and 2O which correspond to the elements 7 8, 9 and 10, of Figure 1. The power for energizing the corona discharge members is supplied lfrom the source 13.

The modification illustrated by Figure 3 has members 21 vand 22 corresponding to members 1 and 2 of Figure 1, which are energized from a source 23 to provide a corona discharge in the same manner as'in the modiiication illustrated by Figure 1. The modulating potential in this modification is applied between two control or grid members 26 and 26 which `are interposed between members 21 and 22. Members 26 and 26 are connected by a. circuit including the secondary of transformer 27, resistance 28 and the battery 29. A` by-pass condenser 30 is shunted around-the resistance and the battery to provide a path for the alternating current component of the varying potential applied to transformr 27. As in Figure 1 the resistance 28 and battery 29 are rovided to obtain the desired grid bias. t may also be advisable to connect one of the members 26 or 26 with one of the discharge membersA -vent the alternating current component ofy the modulating potential from reaching the corona discharge members 21 and 22. The

. control members 26 and 26 may also be laced'sufhciently near the discharge memers 21 and 22 to aliect the corona dlscharge without being located between the discharge members. Various other means ma be employed for modulatin the corona ischarge without applying t e modulating potential to the two d1scharg)e members and accordingly I do not wish to but b the scope of the appended claims.

I c aim: I 1. The method of reproducing sound which consists in providing a corona discharge between two discharge members and in applying a modulating potential to said corona discharge independently of at vleast one of the discharge members.

- 2. A sound reproducer comprisin means including a pair of discharge mem ers for providing a corona discharge, and means for modulating the corona .discharge independe limited by the modifications shown of corona discharge members, means for supplying energy thereto, and means for modulating the corona discharge by a otential applied to amember interposed etween sald 'discharge' members.

` 5. A sound reproducer comprising a pair of members, means for producing a corona discharge between said members, and means for applying a potential to modulate the corona discharge, said means being independent of one of said members.

6. Asound reproducer comprising a pair of members, a source of power for causing an electrostatic discharge between said members, means for applyingia potential to modulate said electrostatic discharge, and a biasing connection between saidmeans and one of said members, said means being otherwise independent of both of said members.

7. A loudspeaker comprising means f or producing a continuous electrostatic d1s charge, and means separate from the first mentioned means except for' a biasing connection for modulating said electrostatic dise lof corona discharge members, Va source of energy for said members, a control member interposed between said discharge members,

and means for applying a modulating potential between said control member and one of said corona discharge members.

9. A loudspeaker comprising a plurality of members, means for producing a corona discharge between said members, and means interposed between said members for controlling said .corona'discharga v 10i A loudspeaker comprising aplurality of members, a source of power for causing a corona discharge between said members, controlling means interposed between said members for controlling said corona discharge, and means for'supplying'a sound modulated potential to said controlling means.

11. A'sound reproducer comprising a `pair of corona discharge members, a source of energy Yfor said, members, a grid member 1nterposed between said discharge members, means for applying a modulating potential between said grid member and one'of said corona discharge members, and means for maintaining a biasing potential between said grid member and one of said corona discharge members. l

12. A sound reproducer comprising a pair of- 'corona discharge members, a source vf energy for said members, a third member polll sitioned between said dischar e members and a connection between said thlrd member and one of said discharge members, said connec- .tion including a secondary of a modulating potential transformer, a resistance, and a battery.

1'3. A sound reproducer comprising a pair of corona discharge members, a source of energy for said members, apair of control members interposed between said discharge members, and means for a plying a modulat ing potential between s ai control. members.v

14. A sound reproducer comprising a pair of members, means, for providing a corona discharge between said members, a pluralityof control members, and means for applying potentials to said control members to modulate said corona discharge. Y

15. .A sound reproducer comprising a pair of corona discharge members, a 'source of energy for saidmembers, a pair of grid-like members interposed between said discharge vmembers, means for applying a modulatingA potential between said grid-like members,

and means for obtaining the desiredv potential relation between one of said id-likemembers and one of said corona lscharge members.

IRVING WOLFF. 

